Susan G. Komen for the Cure, the nation’s leading breast cancer advocacy group, announced on Tuesday that it would stop funding Planned Parenthood centers for breast-health services.

Komen’s officials said that it was severing ties with Planned Parenthood because of a newly adopted policy that prevents Komen from funding organizations that are under government investigation. In September 2011, Congress launched an inquiry into whether Planned Parenthood was using any of its federal money to support abortions, which would violate the terms of its public financing.

Some observers have suggested, however, that the real reason for the rift between the two women’s health advocacy groups has more to do with the abortion debate. Planned Parenthood offers a variety of health services, including birth control, testing for sexually transmitted disease and cancer screening, but it is best known to anti-abortion activists as the largest provider of abortions in the U.S.

The politics aside, how will Komen’s decision affect women who rely on Planned Parenthood for breast-health services? Each year, Planned Parenthood provides 750,000 manual breast exams, and teaches women how to conduct self-exams to detect breast cancer early. While studies have recently questioned the effectiveness of self-exams (current breast-cancer screening guidelines no longer advise doctors to urge women to do self-exams at home), such manual exams at the doctor’s office are still an inexpensive way to screen for cancer and to educate and introduce women to the importance of screening.

Planned Parenthood does not provide mammograms, but does refer women to screening centers, pays for screening for women who cannot afford them, and then follows up with continued care in helping women interpret the tests and take appropriate actions based on their results.

As reported by the Los Angeles Times, Planned Parenthood has provided 4 million breast exams and referred women for 70,000 mammograms over the last five years. In 2010, Komen provided about $680,000 in grants to Planned Parenthood, $100,000 more than it had in 2009. Those funds paid for about 170,000, or 4.5%, of breast exams (in personnel, training and education fees), and 6,400 of the referrals, which included mammograms, ultrasounds and biopsies for women who couldn’t pay for them themselves. That’s a relatively small percentage, but that’s thousands of women who may not have been helped without the funding.

“I find this really disappointing,” Sue Dunlap, chief executive of Planned Parenthood Los Angeles, told the Los Angeles Times. “I think when women’s health is more of a political conversation than a conversation about healthcare and taking care of people, then we’ve gone too far.”

The loss of funding from Komen may disproportionately hurt those who need cancer screening the most. Some Planned Parenthood affiliates use the money to fund outreach programs to minority groups or to those who normally don’t have access to health care. Those programs now risk being terminated, if Planned Parenthood is not able to find additional funding to continue them. So far, the family foundation of Dallas philanthropist Lee Fikes and his wife, Amy, has donated $250,000 to begin to make up the difference, the Associated Press reports.

The split may trigger other moves to withdraw funding — from both groups. Many critics of Komen’s decision are long-time supporters of the group, who gave in small but important ways, by fundraising in the group’s annual race for breast cancer research, for example. “My first 5K ever was for Susan G. Komen. Never will I raise money for this org again,” said one commenter, Jenna Marino, on Twitter. Many others expressed their displeasure on the Komen website; others advised people to donate directly to Planned Parenthood instead.

In a statement, Komen officials expressed regret about the decision but reiterated its commitment to providing women’s health services:

While it is regrettable when changes in priorities and policies affect any of our grantees, such as a long-standing partner like Planned Parenthood, we must continue to evolve to best meet the needs of the women we serve and most fully advance our mission.

A Komen spokesperson, Leslie Aun, stressed that pressure from anti-abortion groups did not play a role in Komen’s decision, and that it was strictly due to new policies regarding funding of entities under Congressional investigation. “We want to maintain a positive relationship with [Planned Parenthood],” she told the Associated Press. “We’re not making any judgment.”

Planned Parenthood’s president Cecile Richards said that she learned of Komen’s decision in a phone call with Komen’s president in December. “It was incredibly surprising,” Richards said. “It wasn’t even a conversation — it was an announcement.”

Richards said she requested a follow-up meeting with Komen’s leaders, but received only a brief letter in reply, ignoring the request and defending the cancer charity’s new grant criteria. The letter added: “We understand the disappointment of any organization that is affected by these policy and strategy updates.”

Regardless of Komen’s true motivations, the possibility that its decision was politically, and not medically motivated leaves many onlookers disappointed with the advocacy group. Even if Planned Parenthood manages to make up for the funding deficit left by Komen’s pullout, it’s clear that hundreds, perhaps thousands, of women could be left without screening services in the meantime.

As Patrick Hurd, CEO of Planned Parenthood of Southeastern Virginia, whose wife is battling breast cancer, said to the AP: “…[C]ancer doesn’t care if you’re pro-choice, anti-choice, progressive, conservative. Victims of cancer could care less about people’s politics.”